Core oil containing a drying oil and asphaltenes



United States Patent CORE OIL CONTAINING A DRYING OIL AND ASPHALTENESHarley F. Hardman, Lyndhurst, and Everett C. Hughes, Shaker Heights,Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, acorporation of Ohio N0 Drawing. Application July 31, 1951, Serial No.239,642

12 Claims. (Cl. 106- 38.7)

This invention relates to core oils or liquid core binders, and moreparticularly to core oils comprislng a drylng oil and asphaltene, andcores made with the same.

In foundry practice, the internal surfaces of most castings are formedwith the aid of sand cores. are prepared from mixtures of sand and asuitable bmder. The binders employed are generally organic substancesand must have certain properties in order to be commercially practical.They must, in the first place, be inexpensive, since the cores are usedin large quantities and the binder is destroyed after use. They must wetsand readily and when mixed with the sand should not adhere to the corebox or mold. They must display adhesive properties when first mixed withthe sand and shaped to form a green core, and this green core must becapable of being baked to a finished core of high tensile and drycompression strength. Since the cores are frequently prepared severalweeks in advance of their ultimate use, the binder must also benon-hygroscopic and must retain its binding properties for a protractedperiod. Finally, the binder must be capable of being burned ofi in orderto recover the sand from used cores.

Heretofore drying oils such as linseed oil have been employed. Thesegive cores of high strengt but unfortunately drying oils are ratherexpensive. Therefore, mixtures of linseed oil with other substancescapable of serving as an extender for the linseed oil have beenproposed, such as a mixture of rosin, linseed oil and petroleum oil.Rosin alone as a binder gives a soft core which readily disintegrates,while linseed oil produces a hard core By varying the proportions of thetwo ingredients, cores having properties intermediate between those ofrosin and linseed oil cores can be prepared which meet existingconditions. However, rosin-containing core oils have the disadvantagethat the rosin tends to crystallize I or sludge, destroying thehomogeneity of the solution and producing a non-uniform core.

In accordance with this invention core oils are prepared comprising adrying oil and an extender consisting essentially of asphaltene in anamount to improve the binding properties of the oil. There is nocritical lower limit of extender concentration for operativeness, theamount used being that required to obtain an improved result. However,there is an upper limit of asphaltene content of about 40% beyond whichno improvement in breaking strength is realized but rather a poorerresult is obtained. Obviously, economy dictates use of as much extenderas possible. Thus the highest percentage of extender which will stillgive favorable cores will usually be used, unless other circumstancesdictate other ratios. However, it will generally not be the mosteconomical and practical to prepare and employ a mixed core oilcontaining less than about 5 to 0f the extender. Thus a desirable rangefor the asphaltene alone is from 5 to about 40% and the optimum range ofasphaltene is from about 7.5 to 30% by weight of the core oil. It istherefore an object of the invention to provide a novel core oilcomprising a drying oil and asphaltenes.

As a further feature of the invention, it has been found, as shown incomparable tests below, that if a mixture of asphaltene and anotherextender comprising petrolene is incorporated in the drying oil, as muchas about 60% extender may be employed with improved results, providedthe amount of asphaltene does not exceed about 40%. Thus with themaximum amount of extender, the

asphaltene should not exceed about 40% with about 20% 8 These cores 'icepetrolene. This use of a mixed extender represents a highly desirableincrease of about 20% over the maximum amount which may be employed ifasphaltene alone is used.

Petrolene when included serves as a diluent for the asphaltene. However,the ratio of petrolene to asphaltene should not exceed about 4 to 1where the maximum amounts of extender is used since amounts of petrolenein excess of this reduce the binding properties of the resulting coreoil considerably below those of drying oil alone. The optimum ratio ofasphaltene to petrolene is between about 1:1 and about 1:2 with theamount of the mixed extender not exceeding about 60% by weight of thecore 'oil composition. Thus another object of the invention is toprovide novel core oils comprising a mixture of a drying oil,asphaltenes and petrolenes.

Combinations of a drying oil and asphaltene in certain definiteproportions unexpectedly give cores having a higher tensile strengththan those produced from core oils composed only of a drying oil or ofasphaltenes. This result is contrary to the results obtained when rosin,for example, or like extender, is mixed with a drying oil. A stillfurther object of the invention is, therefore, to provide improved sandcores for metal casting compris ing sand and novel core oil bindercompositions.

Asphaltenes and petrolenes are components of asphalt. The term asphaltis used herein to apply to both native asphalts and pyrogenous asphalts.Native asphalts include asphalts occurring naturally in a pure or fairlypure state, also asphalts associated naturally with a'substantialproportion of mineral matter, such as sand, sa'ndstone, clay, etc.,which are separated from the asphalt by solvent extraction methods.Pyrogenous asphalts include residues obtained from petroleum by variousmeans, such as distillation (e. g., still bottoms, or residual oil),blowing (e. g., blown asphalts), etc. The term petrolene is used hereinto refer to that portion of asphalt which goes into solution when theasphalt is extracted with 50 volumes of normal pentane. The,termasphaltene is used to refer to that portion of the residue,remaining after pentane extraction, which is soluble in carbondisulfide. Asphaltenes and petrolenes having a relatively largeproportion of non-aromatic hydrocarbons are preferred. Satisfactorynatural mixtures of asphaltenes and petrolenes may be obtained, forexample, from propane precipitated asphalt and asphalt derived from aMid-Continent crude. Linseed oil is the most commonly employed dryingoil in formulating core oils, but other well known drying oils capableof binding sand to produce a core and derived from fish or vegetableoils may be used, such as sardine, menhaden fish, oiticica, tung,walnut, soybean, dehy-' drated castor, perilla, sesame, rapeseed,hempseed, raisin seed, grapeseed, poppyseed, tobacco seed, and mixturesthereof. The term drying oil is used herein to include both drying andsemidrying oils.

The core oil may contain a volatile solvent, preferably one with a slowevaporation rate, so that it is lost only slowly during baking of thecore. Kerosene, petroleum naphtha, mineral spirits and the like aresatisfactory. However, this is not an essential component. Asphaltenesand petrolenes are readily soluble in drymg o1ls, either at roomtemperature or upon warming to about 150 C. For example, they readilydissolve in linseed oil on warming to C. However, in some instancessolubility may be improved by addition of one of the above-mentionedsolvents. Also, certain asphalt fractions are highly viscous, andaddition of a solvent will reduce-the viscosity of the composition to aworkable range.

The core oils are prepared by blending the ingredients, using standardequipment, to form a solution free of suspended or undissolved material.The resulting core oil is then suitable for mixing with sand to producea core.

The. following examples illustrate particular embodi ments of theinvention, but it will be understood that with the above disclosure.

3 EXAMPLE 1 Since dry breaking strength is the property of a core whichis entirely dependent on the binder used, th s property of cores. made?with the core. oils produced. in accordance with the invention: and theprior art. 18 used asav standard of comparison of cone oileifectiveness. The dry breaking strength was measured in the followingway." 100 cc. of sand (Lake Erie, 4080 mesh), 4 cc. of water andaistipulated amount, usually from 2 to. 9 grams, of the core oil. weremixed, formed into green beams 1" x 1" x 6" and. baked for 1 /2 hours atfrom 350 to 450 F. The beams were then cooled, placed on a five inchspan and loaded. at the center at the rate of 24 poundsper minute. Thetransverse strength was taken as the load at the instant the beam broke.All tests were run at room. temperature C.).

Core oils were prepared as listed in. the following table, formed intogreen beams and. baked. The beams were then tested as set. forth in thetest given above, with the following results:

Breaking strengths of test cores Quantity(s) of Core Binder" 7 (e s)Baking Breaking Temp, F.

' Strength,

pounds Composition of Core i'nder Linseed Oil Illinois Asphaltenes.

zene. Coal tar pitch Rosin 50.% 180 M. P. propane asphalt. 50% AtlasClay polymer 1% Lead naphthenate drier.

50% 1;!0" M.. P. propane as 1 1111 t. I 50% Atlas Clay polymer 450 i 1%Lead naphthenate drier. {50% Asphaltenes. I 50% Linseed Oil {25%Asphaltenes.

75% Linseed Oil 25% 180 M. 1?. propane precipitated' asphalt (50%asphaltenes, 50% petrolenes). 75%Linseed Oil 50% 180 M. P. propaneprecipitated asphalt (50% asphaltenes, 50% petrolenes). 50% Linseed Oil75% 180 M. P. propane preeipitated asphalt (50% asphaltenes, 50%pet-rolenes). 25% Linseed Oil 50% 150-160 M. P. oxidized cc. fluxasphaltenes of high aromatic content,

60% petrolenes). Linseed Oil 50% 180 M. P. asphalt from a Mid-Continentcrude (40% asphaltenes, petrolenes). 50% Linseed Oil 50% 210 pen pipestill bottoms (12%%aspl1a.ltenes,

87 petrolenes) 50% Linseed Oil Standard "penetration test.

A comparison of samples 15 and 18 or 21 shows that whereas 50% ofextender composed exclusively of' asphaltenes is excessive, 50% of anextender mixture with a ratio of asphaltene to petrolene of 1:1 is veryadvantageous. This shows the value of petrolenes in permitting anincrease in the total amount of extender tolerable in the composition.

Samples 15 and 16 show mixtures of linseed oil and asphaltene which aresatisfactory and also show that even small amounts of asphaltene in acore oil give stronger cores than those prepared withlinseed oil aloneand this is true up to substantial proportions of added asphaltene.Thus, these samples show that cores of comparable strength tothoseprepared with a drying oil alone can be obtained by incorporating.with: it something less than 50% asphaltene, which by plotting valuesand extrapolating, gives as a maximum value of about 40% asphaltene fora core product which has a breaking strength which is as great as thatprepared with linseed oil alone. Values of asphaltene above this tend tobe less strong and values below 40% are stronger, depending upon thequantity of asphaltene employed. This does not necessarily mean that thestrength of the cores are progressively stronger as the amount ofasphaltene is increased in an amount between 0 and 40% but only thatthere will bea noticeable-increase in strength for various percentagesof added asphaltene up to about 40% an increase which becomesappreciable at a value of added asphaltene of about 25%.

Sample 17 shows that the same increase in breaking strength is availablewhen as much as /2 of the asphaltene is substituted with petrolene andthe asphaltene-petrolene mixture is used in the same percentage in thecore oil. Sample 18 also shows that the same breaking strength for thecore can be realized even if the amount of extender is increasedsubstantially if an asphaltene-petrolene mixture is used in place ofasphaltene alone, i. e., the some breaking strength for the core isrealized with twice as much mixed extender as with 25% added asphaltenealone, which shows that the inclusion of petrolene with asphalteneimproves materially the binding characteristics of the asphalteneextender. Sample 19 shows, however, that a 1:1 asphaltene-petrolenemixture cannot satisfactorily replace of the drying oil without a lossof binding strength, just as 50% of asphaltene alone is too high for.substitution without loss of breaking strength. Thus the maximum amountof the mixed asphaltenepetrolene extender of equal proportions isbetween 50 and or about 60% from a plot of the values.

Sample No. 22 shows that a composition containing 6% asphaltenes and 44%petrolenes (a ratio of 1:7) has too high a ratio of petrolenes toasphaltenes, but sample No. 21 demonstrates that a mixture of 20%asphaltenes and 30% petrolenes (a ratio of 2:3) is satisfactory. Samples16, 17, 18 and 21 demonstrate the optimum proportion of asphaltenes topetrolenes and of both to linseed oil. The limit for the ratio ofasphaltene to petrolene in an asphaltene-petrolene extender mixture for50% substitution for linseed oil can be shown therefore to be about 1:4.

Sample No. 20 shows the effect of a high aromatic hydrocarbon content inthe asphalt, and is to be compared with sample No. 21, where the asphaltwas highly paraflinic in nature. These tests demonstrate that thoseasphaltenes of paraflinic nature are preferable as an extender additiveto core binders.

EXAMPLE 2 Core oils were prepared comprising 40% linseed oil and. 60% M.P. Cleveland asphalt (40% asphaltenes, 60% petrolenes) and made intotest beams as in Example 1. The beams exhibited a breaking strengthsuperior to that of beams made from linseed oil binders.

Although linseed oil is usually employed because of its availability andof economic factors, other drying oils are recognized as useful as corebinders and may be successfully employed in the present invention.Linseed oil is not considered to possess any particular component orproperty which makes it unique for this purpose. Examples of otherdrying oils which can be used are noted above.

Core oils prepared in accordance with the invention produce a good greenbond, and, after baking, display a breaking strength superior to thatobtainable by employing a drying oil alone. Since they are lessexpensive than the commonly-used drying oils, they constitute a usefulcontribution to the art.

All proportions and percentages in the specification and claims are byweight. The invention has been discussed and described by certainspecific examples which will be understood to be illustrative only andnot limiting to the inherent scope of the invention and to themodifications which will be apparent to those familiar with the art fromthe description and claims.

We claim:

1. A core oil consisting essentially of a mixture of a drying oilcapable of binding sand to produce a core and an amount of asphaltene inthe range from about 5% up to about 40% by weight to improve the bindingproperties of the drying oil, said core oil being capable of producing acore having a higher tensile strength than a core produced from a dryingoil alone.

2. A core oil according to claim 1 in which said drying oil is linseedoil.

3. A core oil consisting essentially of a mixture of a drying oilcapable of binding sand to produce a core, an amount of an asphaltene inthe range from about 7.5% to about 30% by weight and an amount of apetrolene in the range from about to about 30% by weight to improve thebinding qualities of the drying oil, the ratio of petrolene toasphaltene not exceeding 4: 1, said core oil being capable of producinga core having a higher tensile strength than the core produced from adrying oil alone.

4. A core oil according to claim 3 in which said drying oil is linseedoil.

5. A core oil consisting essentially of a mixture of a drying oil, anamount of asphaltene from about 5% to 40% by weight, and an amount ofpetrolene not exceeding 30% by weight, the ratio of petrolene toasphaltene not exceeding 4:1, said core oil being capable of producing acore having a higher tensile strength than a core produced from a dryingoil alone.

6. A core oil according to claim 5 in which the drying oil is linseedoil.

7. A core for metal casting comprising a mixture of sand and a core oil,said core oil consisting essentially of a mixture of drying oil and anamount of asphaltene from about 5% to about 40% by weight, the amount ofasphaltone being sufficient to provide a core having a higher tensilestrength than a core containing a drying oil alone.

8. A casting core according to claim 7 in which the drying oil islinseed oil.

9. A casting core according to claim 7 in which the asphaltene comprisesfrom 7.5% to 30% by weight of said core oil.

10. A core for metal casting comprising a mixture of sand and a coreoil, said core oil consisting essentially of a mixture of a drying oil,an amount of ashpaltene from about 5% to by weight and an amount ofpetrolene not exceeding 30% by weight, the ratio of petrolene toasphaltene not exceeding 4: 1, said core possessing a higheitensilestrength than a core containing a drying oil a one.

11. A casting core according to claim 10 in which the amount ofasphaltene is from 7.5 to 30% by weight.

12. A casting core according to claim 10 in which the drying oil islinseed oil.

References Cited in the file of this patent UNITED STATES PATENTS1,778,329 Mason Oct. 14, 1930 1,970,916 Payne Aug. 21, 1934 2,047,297Stahl July 14, 1936 2,256,832 King Sept. 23, 1941 2,444,413 Weston July6, 1948

1. A CORE OIL CONSISTING ESSSENTIALLY OF A MIXTURE OF A DRYING OILCAPABLE OF BINDING SAND TO PRODUCE A CORE AND AN AMOUNT OF ASPHALTENE INTHE RANGE FROM ABOUT 5% UP TO ABOUT 40% BY WEIGHT TO IMPROVE THE BINDINGPROPERTIES OF THE DRYING OIL, SAID CORE OIL BEING CAPABLE OF PRODUCING ACORE HAVING A HIGHER TENSILE STRENGTH THAN A CORE PRODUCED FROM A DRYINGOIL ALONE.